For example, when various devices of an automobile are to be operated by voice of a driver, it is difficult to operate the various devices as intended unless a voice of the driver which is a target sound is appropriately distinguished from a radio voice or the like flowing in the vehicle which is a non-target sound. To extract a target sound under an environment where a non-target sound may exist together with the target sound, there is available a technique using a phase difference between voice signals accepted by a plurality of microphones. The technique calculates a phase difference between voices accepted by a plurality of microphones, identifies a probability value indicating the probability of existence of a target sound existence position based on the calculated phase difference, and suppresses a non-target sound using the identified probability value. Japanese Laid-open Patent Publication No. 2007-318528 is an example of related art.
In a narrow place, such as an automobile interior, however, voice reflects. It is difficult to distinguish between a target sound and a non-target sound based on a phase difference under the influence of the reflection.
The present disclosure appropriately judges a target sound under an environment where the target sound and a non-target sound may be co-resident.